With warm lighting, white brick walls, and a rustic menu full of seasonal fare, The Fat Radish brings healthy British cuisine to the Lower East Side. Opened by two Brits who’ve been friends since boarding school, the restaurant draws plenty of It-Girls and It-Boys eager to sample fresh, unusual finds from the tri-state area’s best farms and markets. Delectable salads, such as the Kale Caesar or Beetroot Swiss Chard, ensure that only the eponymous Radish is fat.